This invention is generally directed to hydroxygallium phthalocyanines, imaging members thereof, and processes for the preparation thereof; and, more specifically, the present invention is directed to processes for obtaining hydroxygallium phthalocyanines, polymorphs or crystal forms, including preferably Type V hydroxygallium phthalocyanine. In one embodiment, the present invention is directed to a process for the preparation of gallium phthalocyanines, especially Type V hydroxygallium phthalocyanines, by providing halo, especially chlorogallium phthalocyanines as illustrated herein; subsequently effecting hydrolysis thereof to a hydroxygallium phthalocyanine, especially Type I; and converting the hydroxygallium phthalocyanine obtained to Type V. The hydroxygallium phthalocyanines, especially the polymorph V, can be selected as an organic photogenerator pigment in photoresponsive imaging members containing charge, especially hole transport layers such as known aryl amine hole transport molecules. The aforementioned photoresponsive or photoconductive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible with toner compositions of the appropriate charge, which toners can be comprised of resin, pigment, charge additive and optional surface additives, reference, for example, U.S. Pat. Nos. 5,114,821; 4,937,157; 4,845,003; 4,904,762; 4,937,166 and 4,935,326, the disclosures of which are totally incorporated herein by reference. Generally, the imaging members are sensitive in the wavelength regions of from about 700 to about 850 nanometers, thus diode lasers can be selected as the light source.
Certain processes for the preparation of hydroxygallium phthalocyanine are known.
For example, in Bull. Soc. Chim. Fr., 23 (1962), there is illustrated the preparation of hydroxygallium phthalocyanine via the precursor chlorogallium phthalocyanine. The precursor chlorogallium phthalocyanine is prepared by reaction of o-cyanobenzamide with gallium chloride in the absence of solvent. More specifically, o-cyanobenzamide is heated to its melting point (172.degree. C.), and to it is added gallium chloride, at which time the temperature is increased to 210.degree. C. for 15 minutes, and then cooled. The solid is recrystallized out of boiling chloronaphthalene to provide purple crystals having carbon, hydrogen and chlorine analyses matching theoretical values for chlorogallium phthalocyanine. Dissolution in concentrated sulfuric acid, followed by reprecipitation in diluted aqueous ammonia, affords a material having carbon and hydrogen analyses matching theoretical values for hydroxygallium phthalocyanine believed to be Type I with major peaks at 6.9, 13.1, 16.4, 21.0 and 26.4.
In JPLO 221459, there are illustrated gallium phthalocyanine compounds with the following intense diffraction peaks at Bragg angles (2 theta +/-0.2.degree.) in the X-ray diffraction spectrum:
1--6.7, 15.2, 20.5, 27.0; PA1 2--6.7, 13.7, 16.3, 20.9, 26.3 (hydroxygallium phthalocyanine Type I); and PA1 3--7.5, 9.5, 11.0, 13.5, 19.1, 20.3, 21.8, 25.8, 27.1, 33.0 (chlorogallium phthalocyanine Type I). PA1 1--6.7, 15.2, 20.5, 27.0; PA1 2--6.7, 13.7, 16.3, 20.9, 26.3; and PA1 3--7.5, 9.5, 11.0, 13.5, 19.1, 20.3, 21.8, 25.8, 27.1, 33.0.
Further, there is illustrated in this publication a photoreceptor for use in electrophotography comprising a charge generation material and charge transport material on a conductive substrate, and wherein the charge generation material comprises one or a mixture of two or more of gallium phthalocyanine compounds with the following intense diffraction peaks at Bragg angles (2 theta +/-0.2.degree.) in the X-ray diffraction spectrum:
In Mita EPO patent publication 314,100, there is illustrated the synthesis of certain, but different photogenerating of titanyl phthalocyanines (TiOPc) by, for example, the reaction of titanium alkoxides and diiminoisoindolene in quinoline or an alkylbenzene, and the subsequent conversion thereof to an alpha type pigment (Type II) by an acid pasting process, whereby the synthesized pigment is dissolved in concentrated sulfuric acid, and the resultant solution is poured onto ice to precipitate the alpha-form, which is filtered and washed with methylene chloride. One specific TiOPc pigment, which was blended with varying amounts of metal free phthalocyanine, could be selected as the charge generating layer in layered photoresponsive imaging members with a high photosensitivity at, for example, 780 nanometers.
In U.S. Pat. No. 4,728,592, there is illustrated, for example, the use of alpha type TiOPc (Type II) in an electrophotographic device having sensitivity over a broad wavelength range of from 500 to 900 nanometers. This form was prepared by the treatment of dichlorotitanium phthalocyanine with concentrated aqueous ammonia and pyridine at reflux for 1 hour. Also described in the aforementioned patent is a beta Type TiOPc (Type I) as a pigment, which is believed to provide a poor quality photoreceptor.
In Konica Japanese 64-17066/89, there is disclosed, for example, the crystal modification of TiOPc prepared from alpha type pigment (Type II) by milling it in a sand mill with salt and polyethylene glycol. This pigment had a strong XRPD peak at a value of 2 theta of 27.3 degrees. This publication also discloses that this new form differs from alpha type pigment (Type II) in its light absorption and shows a maximum absorbance at 817 nanometers compared to the alpha-type, which has a maximum at 830 nanometers. The XRPD shown in the publication for this new form is believed to be similar to that of Type IV titanyl phthalocyanine form described by Sanyo-Shikiso in JOP 63-20365. The aforementioned Konica publication also discloses the use of this new form of TiOPc in a layered electrophotographic device having high sensitivity to near infrared light of 780 nanometers. The new form is indicated to be superior to alpha type TiOPc (Type II). Further, this new form is also described in U.S. Pat. No. 4,898,799 and in a paper presented at the Annual Conference of Japan Hardcopy in July 1989. In this paper, this same new form is referred to as Type y, and reference is also made to Types I, II and III as A, B, and C, respectively.
Generally, layered photoresponsive imaging members are described in a number of U.S. patents, such as U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material which is incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
In copending application U.S. Ser. No. 537,714 (D/90087), the disclosure of which is totally incorporated herein by reference, there are illustrated certain photoresponsive imaging members with photogenerating titanyl phthalocyanine layers prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance as low dark decay characteristics result and higher photosensitivity is generated, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example, U.S. Pat. No. 4,429,029.
In U.S. Pat. No. 5,153,313 the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of phthalocyanine composites which comprises adding a metal free phthalocyanine, a metal phthalocyanine, a metalloxy phthalocyanine or mixtures thereof to a solution of trifluoroacetic acid and a monohaloalkane; adding to the resulting mixture a titanyl phthalocyanine; adding the resulting solution to a mixture that will enable precipitation of the composite; and recovering the phthalocyanine composite precipitated product.
In U.S. Pat. No. 5,166,339 the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of titanyl phthalocyanine which comprises the reaction of titanium tetrapropoxide with diiminoisoindolene in N-methylpyrrolidone solvent to provide Type I, or .beta.-type titanyl phthalocyanine as determined by X-ray powder diffraction; thereafter dissolving the resulting titanyl phthalocyanine in a mixture of trifluoroacetic acid and methylene chloride; adding the resulting mixture to a stirred organic solvent, such as methanol, or to water; separating the resulting precipitate by, for example, vacuum filtration through a glass fiber paper in a Buchner funnel; and washing the titanyl phthalocyanine product. Examples of titanyl phthalocyanine reactants that can be selected in effective amounts of, for example, from about 1 weight percent to about 40 percent by weight of the trifluoroacetic acidic solvent mixture include known available titanyl phthalocyanines; titanyl phthalocyanines synthesized from the reaction of titanium halides, such as titanium trichloride, titanium tetrachloride or tetrabromide, titanium tetraalkoxides such as titanium tetra-methoxide, -ethoxide, -propoxide, -butoxide, -isopropoxide and the like; and other titanium salts with compounds such as phthalonitrile and diiminoisoindolene in solvents such as 1-chloronaphthalene, quinoline, N-methylpyrrolidone, and alkylbenzenes such as xylene at temperatures of from about 120.degree. to about 300.degree. C.; specific polymorphs of titanyl phthalocyanine such as Type I, I, III, and IV, the preparation of which, for example, is described in the literature; or any other suitable polymorphic form of TiOPc; substituted titanyl phthalocyanine pigments having from 1 to 16 substituents attached to the outer ring of the compound, said substituent being, for example, halogens such as chloro-, bromo-, iodo- and fluoro- alkyls with from 1 to about 6 carbon atoms such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, pentyl-, and hexyl-; nitro, amino, alkoxy and alkylthio, such as methoxy-, ethoxy- and propylthio-groups; and mixtures thereof.
As the solvent mixture, there can be selected a strong organic acid, such as a trihaloacetic acid, including trifluoroacetic acid or trichloroacetic acid, and a cosolvent, such as an alkylene halide, such as methylene chloride, chloroform, trichloroethylene, bromoform and other short chain halogenated alkanes and alkenes with from 1 to about 6 carbon atoms and from 1 to about 6 halogen atoms including chlorofluorocarbons and hydrochlorofluorocarbons; haloaromatic compounds such as chlorobenzene, dichlorobenzene, chloronaphthalene, fluorobenzene, bromobenzene, and benzene; alkylbenzenes such as toluene and xylene; and other organic solvents which are miscible with strong organic acids and which will effectively dissolve the titanyl phthalocyanine in effective amounts of, for example, a ratio of from about 1 to 50 parts of acid to about 50 parts of cosolvent such as methylene chloride. In an embodiment, one solvent mixture is comprised of trifluoroacetic acid and methylene chloride in a ratio of from about 5 parts of acid to about 95 parts of methylene chloride to about 25 parts of acid to about 75 parts of methylene chloride. Subsequent to solubilization with the above solvent mixture and stirring for an effective period of time of, for example, from about 5 minutes to several days, the resulting mixture is added to a solvent that will enable precipitation of the desired titanyl phthalocyanine polymorph, such as Type IV, which solvent is comprised of an alcohol, such as an alkylalcohol including methanol, ethanol, propanol, isopropanol, butanol, n-butanol, pentanol and the like; ethers such as diethyl ether and tetrahydrofuran; hydrocarbons such as pentane, hexane and the like with, for example, from about 4 to about 10 carbon atoms; aromatic solvents such as benzene, toluene, xylene, halobenzenes such as chlorobenzene, and the like; carbonyl compounds such as ketones such as acetone, methyl ethyl ketone, and butyraldehyde; glycols such as ethylene and propylene glycol and glycerol; polar aprotic solvents such as dimethyl sulfoxide, dimethylformamide and N-methyl pyrrolidone; and water, as well as mixtures of the aforementioned solvents, followed by filtration of the titanyl phthalocyanine polymorph, and washing with various solvents such as, for example, deionized water and an alcohol, such as methanol and the like, which serves to remove residual acid and any impurities which might have been released by the process of dissolving and reprecipitating the pigment. The solid resulting can then be dried by, for example, heating yielding a dark blue pigment of the desired titanyl phthalocyanine polymorph, the form of which was determined by the composition of the precipitant solvent. The polymorphic form and purity of the product was determined by XRPD analysis.
In working Examples II and IV of the aforementioned U.S. Pat. No. 5,166,339 it being noted that the preparation of X titanyl phthalocyanine is described in Example III, there is disclosed the following. A 1 liter three-necked flask fitted with mechanical stirrer, condenser and thermometer maintained under an atmosphere of argon was charged with diiminoisoindolene (94.3 grams, 0.65 mole), titanium tetrabutoxide (55.3 grams, 0.1625 mole; Aldrich) and 650 milliliters of 1-chloronaphthalene. The mixture was stirred and warmed. At about 140.degree. C. the mixture turned dark green and began to reflux. At this time, the condenser was removed and the vapor (this was identified as n-butanol by gas chromatography) was allowed to escape until the reflux temperature reached 230.degree. C. The reaction was maintained at about this temperature for one and one half hours then was cooled to 15.degree. C. Filtration using a 1 liter sintered glass funnel and washing with boiling DMF, then methanol, provided 69.7 grams (74 percent yield) of blue pigment which was identified as Type I TiOPc by XRPD. Elemental analysis of the product was: C, 67.38; H, 2.78; N, 19.10; Ash, 13.61. TiOPC requires: C, 66.67; H, 2.80; N, 19.44; Ash, 13.61. A 20 milliliter aliquot of a solution of 10 grams of Type I TiOPc prepared in N-methylpyrrolidone solvent in 100 milliliters of a mixture of trifluoroacetic acid in methylene chloride (1:4, v/v) was added over a 2 minute period to a rapidly-stirred solution of methanol (45 milliliters) and water (135 milliliters). The resultant coarse suspension was stirred at room temperature for 35 minutes then was allowed to settle. The supernatant liquid was decanted and the blue residue was redispersed in 100 milliliters of methanol by stirring for 15 minutes. The suspension was filtered using a 7 centimeter diameter glass fiber filter in a porcelain funnel. The solid was washed in the funnel with 2.times.10 milliliter portions of methanol, 4.times.20 milliliter portions of deionized water and 2.times.10.times.20 milliliter portions of water and 2.times.10 milliliter portions of methanol. The solid was dried at 75.degree. C. to yield 1.85 gram of blue pigment identified as Type IV TiOPc by XRPD.
Disclosed in U.S. Pat. No. 5,189,156 is a process for the preparation of titanyl phthalocyanine Type I which comprises the reaction of titanium tetraalkoxide and diiminoisoindolene in the presence of a halonaphthalene solvent; and illustrated in U.S. Pat. No. 5,206,359 is a process for the preparation of titanyl phthalocyanine which comprises the treatment of titanyl phthalocyanine Type X with a halobenzene. The disclosures of each of these patents are totally incorporated herein by reference.
Illustrated U.S. Pat. No. 5,384,223 the disclosure of which is totally incorporated herein by reference, is a photoconductive imaging member comprised of a supporting substrate, a photogenerating layer comprised of photogenerating pigments dispersed in a polystyrene/polyvinyl pyridine A.sub.n -B.sub.m block copolymer wherein n represents the number of segments of the A monomer comprising the A block, and m represents the number of segments of the B monomer comprising the B block, and a charge transport layer.
Disclosed in U.S. Pat. No. 5,164,493 is a process for the preparation of titanyl phthalocyanine Type I which comprises the addition in a solvent of titanium tetraalkoxide to a mixture of phthalonitrile and a diiminoisoindolene, followed by heating. The disclosure of this application is totally incorporated herein by reference.
The disclosures of all of the aforementioned publications, laid open applications, copending applications and patents are totally incorporated herein by reference.